A question mark remains over Robbie Kruse - but Queensland Roar coach Frank Farina has more than the exciting youngster's fitness to worry about.

Farina admits Kruse is "struggling" but will give the striker until Saturday to prove his fitness for Queensland's A-League clash with arch rivals Sydney FC on Sunday.

Farina may be sweating on Kruse who suffered a hamstring injury in last round's heartbreaking 2-1 loss to Melbourne, but he admits his nerves will be truly tested as the Roar vies for a maiden premiership.

Queensland is locked on 30 points with Sydney FC - one behind leader Central Coast - with two regular season games left.

It's enough to make even the experienced Farina consider chewing his nails.

"For it (the premiership] to come down to the wire is not too good for the nerves and the hearts of the coaches, but it could happen," he told reporters in Brisbane.

"If we win though it will put us in a good position going into the last round."

A record Suncorp Stadium crowd is expected to cheer on the Roar in what looms as the most important game in their short history.

"If the boys can't get themselves up for this one, mentally, they'll never get themselves up," Farina said.

"So they're all desperate to go out and do well and I hope that we can do that for everyone on Sunday."

Winger Michael Zullo is set to return for the first time in six weeks after overcoming a thigh strain.

But Farina will be without Reinaldo (suspended), Stuart McLaren (ankle) and Korean defender Hyuk-Su Seo (calf).

"I'd like to be in Sydney's position where you've got everyone available," Farina said.

"We're a few down with the likes of Stuart, Hyuk-Su and Robbie's struggling, Reinaldo's suspended.

"It would be nice to have everyone to choose from, but we don't."

Farina was still keeping his fingers crossed for Kruse who completed some sprint work on Friday morning.

"He's better than expected. But we'll see what happens tomorrow," he said.

"It's one thing doing controlled running but when you talk about hamstrings, it's really when you're doing that explosive stuff that you're going to find out where it's all at.